Grinding wheel truing mechanism



Dec. 4, 1956 c. H. JONES, JR 2,772,670

GRINDING WHEEL mums MECHANISM 4 Sheets-Sheet 1 Filed April 19, 1954 HUI /Nl ENTOR CHA PL 5 h. JONEiJ/E ATT'VS.

Dec. 4, 1956 c, JONES, JR 2,772,670

GRINDING WHEEL TRUING MECHANISM Filed April 19, 1954 4 Sheets-Sheet 2 /N VENTOR CHA RL ES H. JONEQJR. wm mi-Am Arr'rs.

C. H. JONES, JR

GRINDING WHEEL TRUING MECHANISM Dec. 4, 1956 4 Sheets-Sheet 3 Filed April 19 1954 lNVENTOR CHARLES h. JONES 'JP. wu md k AT T Y5- Dec. 4, 1956 c. H. JONES, JR 2,772,670

GRINDING WHEEL TRUING MECHANISM 4 Sheets-Sheet 4 Filed April 19, 1954 vw n 5 CHA PL ES H. JONES, JR.

5 K9410, M im A r rrs.

-- partly in section.

. GRINDING WHEEL TRUENG MECHANISM Charles H. Jones, Jr., Lunenburg, Mass., assignor to Gould Engineering and Sales Co., Inc., Leominster, Mass., a corporation of Massachusetts Application April 19, 1954, Serial No. 423,984

10 Claims. (Cl. 125-11) This invention relates to grinding wheel truing mechanism, more particularly to a device for truing a grinding wheel cutting surface which is complex in shape, that is, which has a normal section which may be concave, convex or a combination of one or more of these with one or more straight portions.

In the truing of the cutting surfaces of grinding wheels, particularly large wheels, it has been diflicult to provide a pivot mechanism on which a truing tool may he swung on a radius to cut a convex shape because the pivotal axis passes through the wheel. Therefore, the pivotal mechanism has had to be located at a considerable distance from the truing tool above or below the wheel, thus making necessary a mechanism of great bulk and strength in order to provide a mounting which is sutliciently rigid to support the truing tool with accuracy as it moves around the radial periphery of the wheel face.

My invention provides a pivoting mechanism which is displaced from the actual pivotal axis around which the ,tool swings, so that it can be located directly adjacent the cutting face being trued, thereby making possible a much more compact mechanism, particularly since the distance between the pivot point of the truing mechanism and the tool is much decreased.

It is, of course, well known that in the motion of the truing tool along a cutting surface of arcuate section,

the point of the tool must be maintained constantly normal to the surface, in other words radially with respect to the center of the are through which the tool is moved. The mechanism of the invention accordingly also provides means by which the tool axis is maintained in such a constantly radial position as the tool is swung in an arc across the wheel face.

When the wheel cutting face includes a straight line section, the truing tool must also be moved along a straight line during a portion of its motion, as well as swung through an arc.

Accordingly, my invention also provides means to move the truing tool along a straight line, means to lock the pivotal movement at a desired point while the tool is being moved in the rectilinear portion of its movement, and means to maintain the tool in an indexed position with respect to its rectilinear movement while it is beingmoved pivotally.

= vice of the invention.

- Fig. 4 is a schematic plan view' of the mechanism of the invention associated with a grinding wheel.

Fig. 5 is a side view of the mechanism ofthe invention,

United States Patent 0 ICC Fig. 6 is a plan view of some of the details of the mechanism.

Fig. 7 is an elevation, partly in cross section, of part of the device of the invention including the truing tool.

Figs. 8, 9, 10 and 11 are top plan views of part of the indexing mechanism showing progressive relationship of the parts during operation.

Figures 1 and 3 show the truing mechanism of my invention, generally indicated at 10, including the truing tool 11, which may be the usual diamond mounted on a cylindrical base 12 held by a set screw 14 as seen in Fig. 7 in a cylindrical mount 16 and having a longitudinal axis indicated by the line 13, which for convenience in description I call the truing tool axis. In these particular figures, the truing mechanism 10, which has a base 26 shown adjustably positioned with respect to a grinding wheel 15 on a conventional magnetic chuck 14, is arranged to true the cutting surface S of the grinding wheel 15. The cutting surface S has a rounded or arcuate section having a radius R through an angle A, which in this case is from one side to the other of the grinding wheel. The mechanism 10 is arranged to pass the point of the truing tool 11 in an arcuate path from one side face of the wheel 15 to the other on the radius R while maintaining the truing tool axis 13 in a constant radial position so that the tool point remains normal to the surface S during its motion, that is, with the axis 13 always passing through the center of the radius R, thereby to generate the surface S as the grinding wheel rotates relative to the truing tool 11.

Figure 1 shows the truing tool 11 on the left-hand side of the wheel at the beginning of the truing operation and Fig. 3 shows the tool on the right-hand side of the wheel after it has passed through the angle A of 180.

Figures 2A, 2B, 2C and 2D, inclusive, show various other shapes of grinding wheel cutting surfaces which may be generated by the same truing mechanism 10, some of which may have sections including straight lines and others of which may include concave surfaces and which will be described in greater detail in connection with further description of the structure and operation of the mechanism.

In Fig. 3, it will be apparent that while the point of the truing tool 11 is passed during a truing cycle around a pivotal axis which passes through the center of the radius R, and therefore through the body of the grinding wheel 15, the mechanism which supports the truing tool 11 is displaced from such a pivotal axis so that it may be located closely adjacent the line of contact between the truing tool 11 and the surface S with the resulting advantages of great strength and compactness.

The mechanism for moving the truing tool 11in the above described arcuate path may perhaps best be understood by first referring to the simplified plan view schematic diagram thereof in Fig. 4. The mechanism 10 comprises in part what may be designated as a parallelogram motion, comprising a pair of arms 20 and 21, see also Figs. 1, 3 and 5, of equal operating length and pivoted respectively at 24 and 25 on the base 26, and 21 long arm 30 having portions 31 and 32 and which is pivotally attached to the outer ends of the arms 20 and 21 at 34 and 35, respectively. The portion 31 of the arm 30 between the pivots 34 and 35 is equal in length to the distance between the pivots 24 and 25. Thus the arm 30 may be moved bodily through an arc, the radius of which is equal to the length of the arms 20 and 21 between pivots, and at the same time the arm 30 remains parallel to a line through the fixed pivots 24 and 25. The arms 20 and 21 have belt drums 39 and 40 fixed concentrically with their pivots and connected by belts 41,

' 42, preferably steel and arranged as seen in detail, in

Figs. 5 and 6. These belts serve to keep the arms '20 -.and 21.synchronized and parallel in all rotative positions,

particularly at dead center position when the arms are in line with the fixed pivots 24 and 25.

A stop pin 14, also seenin Figs. 1 and-3, is provided conveniently on the arm to cooperate with-adjust- -ably positioned stops 45-and- 46 on-the base '26 to'limit the rotative movement of the--arms 2f), 21 and: withinl-SO from one side of the grinding wheel'15 to the -'other. Thus themechanism may be adjustedso that a pivot 50 on the end of the arm portion-32-may move in an are through an angle of 180, the center of which are islocatedat'the center'of'the-radius Rwhich is also the center of the: arcuate cutting surface S to'be generated and on a line through the pivots 24,25. 'The position of thebasemay be adjusted by ones moving it on the chuck 14 to cause the pivots'24, 25 to'line up with the center of the are to be trued.

Mounted concentric to the pivot 35 and fast on-the arm -21 is a belt drum 6%, also seen in Fig. 5, and pivotally -mounted at on the arm 32 is a truing tool support head62, also seen in Figs. 1, 3 and 5, having a fast thereto another belt drum 64, which rotates with the-tool head -62. A belt 65, preferably steel, Fig. 5, connects the belt drums and 64 so that they rotate synchronously in space.

In operation it will be seen that as the arms 20 and 21 are rotated around their respective pivots 24-and '25, for-instance, through an angle'of 135 to the dotted line position, as shown in Fig. 4, the point P on the belt drum 60, which is fixed to the arm 21, also rotates-through an angle of 135 aroundthe pivot 25, while the arm 30 remains, in its dotted line position, parallel to its original position, causing a relative rotation of 135 between the belt drum 60 and the arm extension 32. This relative rotation is transferred through the belt 65 to the belt drum 64 and hence to the truing tool ll through its support head 62, which is integral with the belt drum-64, with the result that the truing tool axis 13' is also then swung through an angle of 135, thus causing the truing tool axis 13 continuously to intersect the center of the radius R and to remain in a constantly radialaspect during its movement. Consequently, the point of the truing tool 11 moves in a circular arcuate path around the surface S having the radius R, the radius R being equivalent to the length of the arm 20 or 21'minus'the distance from the pointof the tool 11 to its pivot 50.

Thus far, for purposes of illustrating the principles of operation, the description has been liirnted to the -truing of a convex grinding'wheel cutting surfaceSextend- 'ing from one side face of the wheel to the other, but by various adjustments and the use of additional means the machine may be adapted to other shapes, including combinationsof arcs and straight lines, Figs. 2A, 2B and 2D, and concaveshapes, Fig. 2C.

As seen in Figs. 1, 3 and 5, the arms- 26 'and 21 have slideways and 71 each containing an adjustablyposiening or shortening the distance between the point of. the truing tool 11 and the axis of its pivot 50.

By reference again for simplicity to Fig. 4, it will be seen that when relative adjustments by the means just described may be made betweenthe efiective length of the 1arm. 21 andthe'distance between- .thepoint ofthe truing '.tool' 11 andlits pivot.50 so thatthe'truing tool p oint may be made to-move along an arc to generate: aconcave "on hollow cutting surface on avgrinding wheel of a type shown in Fig.- 2C.

The desired effect is therefore produced by a combination of the pivoting truing tool support means 62, the support arm means 30 for moving the tool support pivot bodily through a predetermined circular arc, and the associated means, including the belt 65 and the belt drums 60 and 64, for turning the truing tool on its pivot in direct relation to its arcuate movement so as to maintain the truing tool axis 13 constantlyin a radial position with respect to the center of the arc.

"*As'previously stated, the mechanismmaybe adjusted to swing the pointof the'truing'tool '11 through-an arc of predetermined radius and having its centenat' any predetermined point.

The angularity of the arcuate shape of the cutting surface may be limitedby' adjustment'ofthe stops 45 and 46, which act to limit the swinging of the arms 20 and 21 and hence the bodily arcuate movement of the truing tool 11, in cooperation with the stop 44 under the arm 20.

As has been previously mentioned, provision is also made by means about to bedescribed for'moving the truingtool rectilinearly and tangentially with respect to the arcuate'cutting surface shape which may *be 'generated in order to true a grinding wheel having a cutting surfaceof a complex shape, including acombination of arcuate and straight linedsections of the type illustrated in Figs. 2A, 2B and 2D.

Mounted on the truing tool pivoting head .62 and intermediate the' truing tool and its pivot 50 isanindexing mechanism of the type described and claimed in copending application Serial N0. 418,398. Thisscompris'es a slideway 85, Fig. 7, on the tool head 62 and a' cooperating slide 86 thereon containingnthe sleeve-80, the tool mount. 16 andithe truing tool 11, whereby the'tool 11 may be moved rectilinearly along its support'head'62.

Rotatively seated in-the slideway is a rotatable member in the form of a sleeve-shaped plug'90 adjacent the un- 1 tion, as viewed'in Figs. 8-11.

-tion 96 enters the widened track portion 98 during movement of the slide 86 along the slideway 85.

'When the slide-86 is moved relative to the s'lideway and the rotatable member 90, the track '95'is engaged by the raised portion 96 of the plug 90, thus preventing the latter from turning. When the rotatable raisdpor- 'tion 96 reaches the widened portion 98', as 's'een'in'Fig.

11, it allows the rotatable raised porti'on=96to -turnin a "counterclockwisedirection as viewed, 'until' the faces 99 and 100 'of the widened track portion engage the rotatableraisedportion'96, as seen in Fig. '10, against the force of the spring 91. 'Atithis' stage the rotatable member resists further movement'of the slide 86' on the slideway 85, thus providing an indexed position of v the turning tool 11 with respect to its rectilinear movement. When, 7 however,- an excess force is applied to move the slide'86 alonglthe'slideway '85 out of its-indexed position, the face of the widened track portion 98 forces the rotatable member 90. in a counterclockwise direction, as seeninFig. 11, causing-the raised portion 96 againtoline up inthe extension of the-tracle98allowing the slide 86 to be moved further.-- along the-slide- Way-85, or alternatively in the reciprocal direction. I In other words, the indexing mechanism has the same action when theslide is moved to and from the indexed position in either direction. T The movementof the slide 86' relative -totthe center-of the rotatable member" 90 is exaggerated in Figs. 9 and 11 since such movement willbe almost-imperceptible during rotation of the rotatable member 90 shown in these three figures.

In Fig. 7 is seen a rotatable operating member 103 received and retained by a set'screw 101 in the body of the slide 86. It has conveniently an operating handle 105 for manual rotation and a gear 108 engaging a rack 110 fast in the slideway 85, thus providing increased leverage and precision and ease of operation for movement of the slide along the slideway in either direction.

by rotation of the handle 105.

The truing tool pivoting head 62 has a handle 115 for pivotal operation of the tool rotating mechanism 10 as a whole between predetermined limits established by adjustment of the stops 45 and 46.

For truing a cutting surface of the type illustrated in Fig. 2A, the mechanism is adjusted by the parts above described so that the tool may be pivotally moved in an arc having a desired radius and angularity to coincide with the arcuate portion 16b of the cutting surface as shown, while the slide 86 is in the indexed position illustrated in Fig. 10. For this purpose the base 26 is positioned so that the pivots 24, 25 are in line with the center of the arc 16b. The mechanism is then pivotally swung over against the stop 46 by means of the handle 115 in a clockwise direction, from the position illustrated in Fig. 3. The slide 86 is then moved to the left by motion of the handle 105 to the left, as viewed in Fig. 3, to move the truing tool 11 far enough to the left so that it will intersect the left-hand side of the grinding wheel 15a, Fig. 2A, when the entire mechanism is swung over to the left-hand position, as the operator faces the machine, as shown in Fig. 1. With the mechanism held against the stop 46, the operator then moves the handle 105 toward the front of the machine, thus bringing the truing tool rectilinearly along the straight portion 16a from the position marked I in Fig. 2A to the position marked II in Fig. 2A, at which point the slide 86 is now in the indexed position, illustrated in Fig. 10, locking it temporarily against further rectilinear movement. The mechanism is now pivotally swung by the handle 115 from the stop 46 to the stop 45, as illustrated by the position marked III, during this movement to generate the arcuate portion 16b of the cutting surface in Fig. 2A. Thereafter, the handle 105 is moved out of the indexed position further to move the slide 86 in the same direction as previously to generate the straight portion 16c in Fig. 2A, after which the tool may be passed back over the surface in the reverse direction or else withdrawn in some other convenient manner, as by retraction of the adjusting screw 82.

The truing of the cutting surface in Fig. 2B, comprising the straight portion 17a and the arcuate portion 17b, is done in essentially the same manner, with the creeption that one of the rectilinear passes is omitted. Adjustments are made to locate the center of the are 1717 and to correspond with its radius and angularity, thus also establishing the angularity of the straight portion 17a. The truing pass can be done from either direction as preferred, the mechanism being held against the preadjusted stop 46 while the rectilinear surface 17a is being trued, and the slide 86 being in the indexed position of Fig. 10, while the arcuate portion 17b is being generated by pivotal movement of the mechanism between the stops 46 and 45.

The cutting surface 18a and 18b of Fig. 2D is generated in the same manner as in the operation for Fig. 2B, except that the parts are adjusted for a smaller radius and greater angularity of the arcuate part of the surface 18b.

The genertion of the concave surface H, shown in Fig. 2C, has been described in connection with the description of Fig. 4 and it will be apparent that concave surfaces may be combined with surfaces having rectilinear sections in the same manner by adjustment of the parts.

Fig. 6 shows details of the manner of using a double 6 steel beltv 41-42 tensioned by eccentrically mounted idlers 43 and 47 for precisely synchronizing the rotation of the belt drums 39 and 40 more precisely to preserve the accuracy of operation of the pivoting mechanism 10.

Other mechanical details, including the. use of adequately accurate bearings and other structural parts, will be apparent from the drawings, the combination of essential means for performing the described functions of the mechanism, comprising the essence of my invention, which is therefore not intended to be limited to the particular details shown.

It will be apparent that the base 26 may be fixedly mounted and adjustments made to establish the relation of the pivots 24, 25 with the wheel by motion of the wheelhead by the conventional hand wheel or other means, or that the base 26 may be mounted on a table which may be moved to make these adjustments.

I claim.

1. Grinding wheel truing mechanism including a truing tool, indexing means for the tool comprising a first and a second element, said tool being supported in one of said elements, said elements being adjacent and relatively movable in a predetermined path, a rotatable member seated in said second element adjacent said first element, a spring urging said rotatable member to turn, a track in said first element corresponding to said path, said rotatable member having a raised portion slidably engaging said track, said track having a widened portion including cooperating faces angularly disposed to said track which are offset from each other thereby allowing said rotatable member to turn within limits when its said raised portion enters said widened track portion during relative movement of said elements, said angularly disposed faces engaging said raised portion against the force of said spring when the rotatable member is in said turned position thereby causing said rotatable member to resist further relative movement of said elements.

2. Grinding wheel truing mechanism to move the point of a truing tool along an arc across the face of a grinding wheel while the axis of the tool remains radial to the center of the arc, comprising in combination a truing tool, a pivot for the truing tool, a pair of crank arms each having an axis of rotation which is displaced from the central axis of the are a support arm pivotally connected between the cranks equidistantly from their centers thereby providing a parallelogram mechanism said support arm having an extended portion which supports said pivot for moving the pivot bodily through the arc; and means connected between one of the crank arms and the pivot to rotate the tool in equal angular relation to the arcuate movement of the pivot.

3. In the combination as set forth in claim 2, means for adjusting the distance between the support arm and the centers of the crank arms.

4. In the combination as set forth in claim 2, means to adjust the distance between the tool point and the tool pivot.

5. In the combination as set forth in claim 2, means adjustably to limit the arcuate movement of the pivot to a predetermined angle.

6. In the combination as set forth in claim 2, slide means between said pivot and said tool arranged to provide rectilinear movement of said tool with relation to said pivot.

7. In the combination as set forth in claim 6, a rack on said slide means, a pinion engaged to said rack to operate said slide means, and means to rotate said pinion.

8. In the combination as set forth in claim 6, indexing means associated with said slide means for establishing a predetermined rectilinear relationship between said tool and said pivot.

9. Grinding wheel truing mechanism to move the point of a truing tool along an arc across the face of a grinding wheel while the axis of the tool remains radial to the center of the arc, comprising in combination a truing tool, a pivot for the truing tool, a pair of crank arms each having an axis of rotation which is displaced from the central axis of the arc, a support arm pivotally connected between the crank arms equidistantly from their centers thereby providing a parallelogram mechanism, said support arm having an extended portion which supports said pivot for moving the pivot bodily through the arc, a belt drum fixed on one of the crank arms, a belt drum fixed tozthe pivot, and a belt connecting the belt drums to rotate the tool in equal angular relation to the arcuate movement of the pivot.

10. Grinding wheel truing mechanism to move the point of a truing tool along an arc across the face of a grinding wheel and along a straight line tangent to the arc'comprising a truing tool, support means to move the truing tool through an'arc while maintaining the tool in a position which is radial to the center of the arc, a first and a second element mounted on said support means, said tool being supported on one of said elements, said element being adjacent and relatively slidable in a straight line, a rotatable member seated in said second element adjacent said first element, a spring urging said rotatable member to turn, a track in said first element parallel to the direction of said slidable movement, said rotatable member having a raised portion slidably engaging said track, said track having a widened portion including cooperating faces angularly disposed tpisaid track which are References Cited in the file of this patent UNITED STATES PATENTS 1,250,359 Sacrey Dec. 18, 1917 1,841,852 Snarry Jan. 19, 1932 2,109,454 Becker Mar. 1, 1938 2,332,013 Rudert Oct. 19, 1943 2,346,528 Welsand Apr. 11, 1944 2,469,844 Porter May 10, 1949 2,581,980 Suber Jan. 8, 1952 2,665,680 .Gotberg Jan. 12, 1954 FOREIGN PATENTS 10,011 Great Britain May 1 2, .1899 406,838 Great Britain Mar. 8, 1934 

